1. Technical Field
This disclosure generally relates to image forming methods, image forming devices, and image forming programs, and more specifically, to an image forming method of detecting an image writing position, synchronizing, and adjusting the image writing position in order to adjust the image writing position to a transferring material, an image forming device, and an image forming program.
2. Description of the Related Art
Presently, in an image forming device such as a PPC (Plain Paper Copier), based on a printing mode such as a sheet size, sheet kind, or a color mode (color or monochrome) selected by the user or the state of an image forming part, various processes are implemented inside the image forming device so that proper printing quality or printing properties are realized.
For example, adjustment of printing starting position is one of various processes.
Here, an image forming method of the image forming device and the adjusting method of the printing starting position are discussed.
In the image forming method, a laser beam generated by a visible semiconductor laser of an LD (Laser Diode) is rotationally scanned by a polygon mirror. The polygon mirror is a rotating member having four through six plane reflection surfaces. While the polygon mirror is rotated at high speed at several ten thousand rotations per minute, an image is formed. The rotation of the polygon mirror is controlled by a driving motor at a constant speed.
The beam is irradiated on a photosensitive body via a fθ lens so that an image is formed. More specifically, the fθ lens collects the beam deflected by a scanner such as the polygon mirror on a plane image surface for scanning.
Thus, since an irradiation starting position on a main scanning line on the photosensitive body, namely the printing starting position, is determined by the rotational position of the polygon mirror, the rotational position of the polygon mirror should always be known in order to maintain the printing quality.
Because of this, when the rotation of the polygon mirror becomes stable, the semiconductor laser is turned on so that a light path is fixed by the polygon mirror. A proper position is detected by a detection element provided at an end part in the main scanning direction on the irradiated photosensitive body so that synchronization for determining the rotational position of the polygon mirror is detected.
By the above-mentioned method, the manufacturer adjusts a proper printing starting position and maintains printing quality for the user.
However, since the light beam emitted by the semiconductor laser reaches the photosensitive body, exposure of the photosensitive body occurs by adjustment of the image writing position so that a latent image is formed and toner is applied. As a result of this, a toner is adhered on a transferring belt.
In a case where printing is implemented after the printing starting position is adjusted, the toner adhered on the transferring belt can make the rear surface of a fed sheet dirty so that the printing quality is degraded
Because of this, in order to solve such a problem, a method for separating the photosensitive body from the transferring member or a method for making the voltage output to the transferring member low has been suggested. See Japanese Laid-Open Patent Application Publication No. 9-6151 and Japanese Patent No. 2640760.
However, as discussed in Japanese Laid-Open Patent Application Publication No. 9-6151, in the method for separating the photosensitive body from the transferring member, it is difficult to form a structure where the photosensitive body is separated. Therefore, this causes a large size of the product and increase of cost of the product. Furthermore, the printing property (printing speed) such as fast printing is decreased.
In addition, as discussed in Japanese Patent No. 2640760, in the method for making the voltage output applied to the transferring member low when a latent-imaged area reaches the transferring position of the transferring member so that transferring from the photosensitive body is prevented, the toner is actually adhered on the photosensitive body. Therefore, if the photosensitive body and the transferring member are not separated, a slight amount of the toner may be adhered due to friction.